Note that \(\mbox{si}(-x)=-\mbox{si}(x)\)  and \(\mbox{ci}(-x)=\mbox{ci}(x)\) . With the help of the identities[1]}
\(& & \! \int ^{+\infty }_0 \! \! dx\sin {(px)}\mbox{si}(qx)=-\frac{\pi }{4p} \\& & =\! \int ^{+\infty }_0 \! \! dx\cos {(px)}\mbox{ci}(qx) \ ,\) 
